The present invention relates to workpiece positioning tables. Positioning tables for workpieces have been known heretofore whereby the workpiece is mounted upon a movable carriage and is directed thereon along a predetermined path selected to advance the workpiece past a series of stations at which selected machining or material forming operations are performed on the workpiece. One such positioning table has been marketed by Anorad Corporation of Smithtown, N.Y. Positioning tables of this character include a base member adapted to reciprocably carry a carriage between a pair of side walls projecting upwardly from the base. It has been conventional to form pairs of corresponding V-notches on inserts which are secured to the carriage and base members to thereby form the ways of the table. Ball or roller bearings are positioned within the corresponding sets of V-notches so as to rollably mount the carriage on the base.
The operations to be performed upon the workpiece generally require that the carriage be accurately aligned both vertically and laterally relative to the base and that such alignment be maintained over a substantial period of the operational longevity of the table. This has not been possible to the extent desired in prior art tables principally because of the need to utilize inserts requiring affixing to the carriage and base members by means such as screws or the like. Although the wear surfaces of the notches have performed satisfactorily the inserts in which the V-notches were formed usually became loose and resulted in misalignment of the corresponding matched notches of the carriage and bed with consequent misalignment of the carriage in the ways. Such misalignment of the carriage led to the production of imperfect workpieces and in excessive wear of the ball or roller elements thereby compounding the problem.
It has also been determined that consequent to the normal operation of the positioning table some degree of lateral "play" of the carriage in the ways developed. Vibratory stresses were induced in the table making it impossible to accurately machine or otherwise form the workpiece. Further, the use of the separate inserts involves the use of materials having different coefficients of heat and leads to distortions and inaccuracies attendant to temperature gradients created in the table during its operation. Loosening of the inserts is aggravated under such thermal conditions.